Stable base mounts

ABSTRACT

In a ship-born stable base mount is a hollow column secured in a position perpendicular to the deck plane of the ship. Means are presented for mounting a Gimbal system including two orthogonal axes on the upper end portion and a gyroscopically controlled servo drive system on the lower end portion of the hollow column. Furthermore, the stable base mount comprises transmission means controlled by the servo drive system and extending through the length of the interior of the hollow column to act on a base member to be stabilized.

[451 May 23,1972

United States Patent Ter Brugge 1,964,869 7/1934Boykow..................................74/5.22

[54] STABLE BASE MOUNTS 3,218,015 11/1965 Baer [72] Inventor: HendrikTer Brugge, l-lengelo, Nether-' lands FOREIGN PATENTS OR APPLICATIONSGreat Britain........,.................74/5.22

Primary Examiner-Manuel A. Antonakas Attorney-Frank R. Trifari [22]Filed:

[21] Appl. No.: 32,700

ABSTRACT 1n a ship-bom stable base mount is a hollow column secured in[30] Foreign Application Priority Data May 8, 1969 a positionperpendicular to the deck plane of the ship. MeansNetherlands..........................6907029 are presented f mounting aGimba] Sysmm including two orthogonal axes on the upper end portion anda gyroscopically controlled servo drive system on the lower end portionof the [52] US. 74/5.8, 114/122 [51] Int. ..,.G0lc 19/46 hollow column.Furthermore, the stable base mount com- 5s FieldofSearch..

prises transmission means controlled by the servo drive system andextending through the length of the interior of the hollow column to acton a base member to be stabilized.

l 1 Claims, 3 Drawing Figures References Cited UNITED STATES PATENTS1,639,233 Paxton..............................,...74/5.6 X

PATENTEDMM 23 I972 3, 664,200

sum 1 or 3 INVENTOR H. TER BRUGGE PATENTEBmzsmn I 3.664.200

SHEET 2 OF 3 INVENTOR H. TER BRUGGE AGENT PATENTEDMAY 2 3 1912 SHEEI 3BF 3 INVENTOR H. TER BRUGGE BY ifiwag,

AGENT STABLE BASE MOUNTS The invention relates to stable base mounts ofthe type comprising a gimbal system including two orthogonal axes, abase member and a gyroscopically controlled servo drive system forstabilizing said base member about said two orthogonal axes.

Such stable base mounts are known and find application aboard ships. Thetwo orthogonal axes are most conveniently named roll axis and pitch axisrespectively; the roll axis lies in a fixed position parallel to thefore and aft line of the ship and supports the pitch axis, which is inparallel to the earth surface.

The base member may constitute or carry a train axis, which may supportan elevation axis, thus extending the arrangement to a three or fouraxes stable base mount. Having no train accelerations due to tilt of thedeck and requiring no computers, such three or four axes stable basemounts are particularly suitable for mounting a radar antenna or othersighting means, such as for instance a television camera and/or infraredcamera, especially when these sighting means have to perform at highrotational speeds as required in searching and/or tracking operations.Their applicability to stabilization problems is, however, severelylimited by the mechanical difficulties encountered. These difficultiesarise from the fact that separate servo drives are needed forcontrolling the rotation about each one of the different axes. As aresult the known stable base mounts are relatively massive and sufferfrom top-heaviness.

It is an object of the present invention to provide a stable base mountin which the above mentioned difficulties have been substantiallyovercome.

According to the invention a shipbome stable base mount of the typecomprising a gimbal system including two orthogonal axes, a base memberand a gyroscopically controlled servo drive system for stabilizing saidbase member about said two orthogonal axes, is provided with a hollowcolumn secured in a position perpendicular to the deck plane, means formounting said gimbal system on the upper end portion and said servodrive system on the lower'end portion of said hollow column, andtransmission means controlled by said servo drive system and extendingthrough the length of the interior of said hollow column to act on saidbase member to be stabilized.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description, when consideredin conjunction with the accompanying drawings, wherein FIG. 1 is aperspective view showing in detail the base member to be stabilized andthe manner in which it is suspended;

FIG. 2 is an over-all perspective view of the stable base mountaccording to the invention; and

FIG. 3 is a perspective view of a preferred embodiment of the servodrive system.

In these figures, like reference numerals denote like parts.

In the following description reference is made to sets of identicalparts, even if only one part of such a set is actually visible in therelevant figure. However, since the arrangement shown is symmetricalwith respect to two orthogonal axes, it will be understood, that theother part of such a set is present in a position symmetrically oppositesaid visible one.

Referring to FIG. 1, reference numeral 1 designates a base member to bestabilized about two orthogonal axes, i.e. a roll axis 2 and a pitchaxis 3. To this end, there is provided a gimbal system comprising a setof identical supports, such as 4, and a gimbal ring 5 having a first setof identical hollow shafts, such as 6 and a second set of identicalhollow shafts, such as 7. Both sets of shafts are rigidly connected tosaid gimbal ring 5 to constitute the said roll and pitch axesrespectively. The first set of shafts constituting the roll axis isrotatably mounted in the supports 4 which are rigid with respect to, forinstance, the deck plane of a ship. The second set of shaftsconstituting the pitch axis is mounted in bearings of base member 1, soas to permit said base member to rotate about these shafts. As may beseen in the figure, base member 1 is hollow and has a cyclindricalportion which extends in the vertical when said base member isstabilized. This cylindrical portion, therefore, may be used directly asa train axis or may carry a platform onto which any type of sightingmeans may be mounted for rotation about a train axis and an elevationaxis.

Base member 1 is held in a given fixed position with respect to a stablereference. The stable reference is provided by gyroscopes 8 and 9, therespective housings of which are secured in the interior of hollowshafts 6 and 7 respectively, as may be seen in the figure. The twogyroscopes have two degrees of freedom. Gyroscope 8 has a spin axis inthe horizontal plane and is orientated in a given direction (for exampleNorth); it is therefore termed the azimuth or directional gyroscope,which supplies synchro-data used, inter alia, for calculatingcorrections required in view of deviations in azimuth owing to yawningof the ship. Since the gyroscope 8 does not play a direct part in thestabilization of base member 1, it will be left out of considerationhere. Gyroscope 9 has a spin axis which by means of the conventionalgyroscopic control means is held in an accurately vertical position.This gyroscope, which is termed vertical gyroscope, supplies at its twooutputs 10 and 11, formed by synchros (not shown), two error voltages,the magnitude and sign of which are a measure of the deviation of basemember 1 from the zero position as determined by the vertical spin axisof the gyroscope. These error voltages are supplied through respectiveservo amplifiers (not shown), to a servo drive system 12 (FIG. 3) to bedescribed hereinafter. This servo drive system, when properly energized,is capable of tilting the base member to be stabilized about the hollowshafts 6 and 7, so that these error voltages are reduced to their zerovalue.

A favorable and particularly advantageous stable base mount is obtainedin that,as shown in the figures, there is provided a hollow column 13secured in a position perpendicular to the deck plane, means 14 formounting said gimbal system on the upper end portion and said servodrive system 12 (FIG. 3) on the lower end portion of said hollow columnand trans mission means 15 controlled by said servo drive system 12 andextending through the length of the interior of said hollow column toact on said base member to be stabilized.

In the preferred embodiment, hollow column 13 is of cylindrical shapeexcept for its lower end portion, which is secured to a delta-shaped box16 enclosing the servo drive system 12. This box is secured to the deck,preferably by means of shock absorbers (not shown) supporting said boxat its three corners.

By mounting the servo drive system in box 16 on the lower end portion ofhollow column 13, instead of mounting it directly onto the gimbalsystem, the weight and size of the gimbal system is materially reducedand hence, the center of gravity will be lower down. Owing to this,hollow column 13 as well as the said shock absorbers may be less heavy.At the same time the shock absorbers can be closer together as theirrelative spacing will be determined mainly by the size of box 16. Hence,a saving of valuable deck space is obtained. Moreover, owing to thereduced massiveness of the gimbal system, the latter may be realized ina manner permitting its total enclosure. To this end, as shown in FIG.1, the set of supports 4 are mounted on a top-plate 14 of column 13 andin a position such that the point of intersection of roll axis 2 andpitch axis 3 is on the longitudinal axis 17 of hollow column 13. The setof shafts constituting the roll axis 2 and the set of shaftsconstituting the roll axis 2 and the set of shafts constituting thepitch axis 3 are both rigidly connected to the gimbal ring 5, so thatthey project inwardly therefrom; the outer diameter of said gimbal ringbeing slightly smaller than the outer diameter of hollow column 13. Basemember 1 is provided with a circular cover plate 18 fixedly connectedthereto and having a circular hole at its center, through which thecylindrical portion of base member 1 protrudes. The outer diameter ofcover plate 18 is chosen to be equal to the outer diameter of hollowcolumn 13. The gimbal system is enclosed by said circular cover plate 18and a rubber bellows 19, the end portions of which are tightly fittedaround the outer circumference of cover plate 18 and hollow column 13,by means of clamp rings 20 and 21 respectively.

In the preferred embodiment of the stable base mount thus far described,use is made of a servo drive system as illustrated in FIG. 3.

Referring thereto, reference numeral 22 designates a frame to bestabilized about two orthogonal axes, i.e. an associated roll axis 23and pitch axis 24. To this end, the stable base mount is provided with asecond gimbal system comprising a set of supports 25, 26 and a gimbalframe 27. Frame 22 and gimbal frame 27 are each provided with a set ofhollow shafts, such as 28 and 29 respectively. Each set of hollow shaftsis rigidly connected to the relevant frame and projects outwardlytherefrom to constitute the roll and pitch axes 23 and 24 respectively.The set of shafts constituting the roll axis 23 is rotatably mounted inthe set of supports 25, 26 so as to permit gimbal frame 27 to rotatewith respect to said supports. These supports are rigidly secured to theinside top wall of box 16 in FIG. 2 and in a position such that thecentral axis 17 of hollow column 13 passes not only through the point ofintersection of roll axis 2 and pitch axis 3, but also through the pointof intersection of roll axis 23 and pitch axis 24; roll axis 2 and rollaxis 23 being in parallel to one another. Gimbal frame 27 is furtherprovided with a gear segment 30 which is fixedly connected to saidgimbal frame. This gear segment is partially enclosed by a gear box 31constituting the lower portion of support 25. Gear box 31 comprises aschematically presented gear train 32 and a reversible electric motor33, which may apply a rotational movement to gimbal frame 27 by drivinggear segment 30 via said gear train 32 in the one or in the other sense.The maximum angle through which gimbal frame 27 may rotate with respectto said supports is limited by stops, such as 34 and 35. These stops areon the outside back wall of the supports 25, 26 and in a positionsymmetrical with respect to the roll axis 23. They cooperate with amember 36 which is fixedly connected to one end of a torsion bar 37extending centrally through the length of said hollow shaft 28. Theother end of said torsion bar is rigidly connected to gimbal frame 27,so that member 36 rotates with gimbal frame 27. The moment said member36 meets a stop, torsion bar 37 operates as a shock-reducing resilientmeans.

The sets of shafts constituting the pitch axis 24 is rotatably mountedin bearings of gimbal frame 27, so as to permit frame 22 to rotate withrespect to said gimbal frame. Frame 22 is provided with a gear segment38 which is fixedly connected to said frame 22. Gear segment 38 ispartially enclosed by a gear box 39 forming part of gimbal frame 27.Gear box 39 comprises a schematically presented gear train 40 and areversible electric motor 41 which may apply a rotational movement toframe 22 by driving gear segment 38 via gear train 40 in the one or inthe other sense. The maximum angle through which frame 22 may rotatewith respect to gimbal frame 27 is limited by steps such as 42 and 43.These stops are on the outside of gimbal frame 27 and in a positionsymmetrical with respect to pitch axis 24. They co-operate withportions, such as 44, 45, projecting from a cover 46. The latter isfixedly connected to one end of a torsion bar 47 extending centrallythrough the length of hollow shaft 29. The other end of this torsion baris rigidly connected to frame 22, so that cover 46 and its projectingportion 44, 45 rotate with frame 22. The moment said projecting portionsmeet a stop, torsion bar 47 operates as a shock-reducing resilientmeans.

Frame 22 and base member 1 are linked to one another in a manner suchthat the cylindrical portion of base member 1 will be in the verticalposition when frame 24 is in the horizontal one. To this end, use ismade of mechanical transmission means 15 which extend through the lengthof the interior of hollow column 13. In the embodiment shown thesetransmission means are constituted by four identical connecting rods.Frame 22 is provided with four shafts such as 48 and 49 which aredisposed in parallel to the roll axis 23 and in positions symmetricalwith respect to the roll and pitch axis 23 and 24 respectively. Likewisebase member 1 in FIG. 1 is provided with four shafts, such as 50, whichare disposed in parallel to the roll axis 2 and in positions symmetricalwith respect to the roll and pitch axes 2 and 3 respectively. Therelative spacing of the four shafts in frame 22 is equal to the relativespacing of the four shafts of base member 1, so that each one of thefour shafts in frame 22 may be said to form a pair with one of the fourshafts of base member 1. The shafts of each pair are interconnected byone of the four connecting rods 15. In connecting these rods to theshafts use is made of spherical bearings such as 51 in FIG. 1 and 52 inFIG. 3, providing two degrees of freedom of motion. Since theseconnecting rods extend through the length of the interior of hollowcolumn 13, the great advantage is obtained that, with the exception ofthe protruding cylindrical portion of base member 1, all moving parts ofthe stable base mount are totally enclosed.

Another advantage of the stable base mount here described is that evenif hollow column 13 is bent, which may happen under adverse conditions,this will not affect the angular position of base member 1, owing to thefact that the identical connecting rods will remain in parallel at alltimes.

Assuming frame 22 in the horizontal position, the cylindrical portion ofbase member 1 will be in the vertical. Any roll and pitch angles appliedto the deck plane will be measured by the vertical gyroscope 9 andcorresponding error voltages occur at its outputs 10 and 11. These errorvoltages are applied to control reversible motors 33 and 41respectively, which tilt frame 22 and hence base member 1 to reducethese error voltages to their zero value.

In the embodiment described use is made of four connecting rods 15, itwill be clear, however, that a smaller number of connecting rods maysuffice.

In the embodiment described, the gyroscope housings are directlyconnected to the base member to be stabilized. This construction,although advantageous, is not essential, as it is also possible toarrange the gyroscopes at a distance remote from the base member to bestabilized, for example in the meta-center of the ship. It is alsopossible to slave the stabilization system to another stable base.

Finally, it may be observed that the stable base mount disclosed herein,is not limited to the use of the servo drive system as shown anddescribed with reference to FIG. 3. Other types of servo drive systems,such as for instance a hydraulic servo drive system, can be used aswell.

What we claim is:

1. A ship-born stable base mount, comprising a hollow column secured ina position perpendicular to a deck plane of the ship, a base member,means for mounting a gimbal system including two orthogonal axes on thetop of the hollow column in a position such that the point ofintersection of the orthogonal axes lies on the logitudinal axis of thehollow column, a gyroscopically controlled servo drive system mounted onthe lower end portion of the hollow column for stabilizing the basemember about the two orthogonal axes, and mechanical transmission meanscontrolled by the servo drive system and extending through the length ofthe interior of the hollow column said transmission means acting on saidbase member whereby said bore member is stabilized about said twoorthogonal axes.

2. A stable base mount as claimed in claim 1, wherein said gimbal systemcomprises a gimbal ring having two sets of hollow shafts projectinginwardly therefrom .to constitute a roll and pitch axis respectively.

3. A stable base mount as claimed in claim 2, wherein one of the hollowshafts constituting the pitch axis accomodates a vertical gyroscopeproducing error voltages which in magnitude and sense correspond to thedeviation of said base member from the zero position as determined bysaid vertical gyroscope.

4. A stable base mount as claimed in claim 1, wherein said hollow columnis of circular cross section and wherein the outer diameter of saidgimbal ring is slightly smaller than the outer diameter of said hollowcolumn.

5. A stable base mount as claimed in claim 1, wherein said base membercomprises a cylindrical portion which extends in the vertical when saidbase member is stabilized.

6. A stable base mount as claimed in claim 1, wherein said base memberis provided with a circular cover plate fixedly connected thereto andhaving a central hole through which the cylindrical portion of said basemember protrudes.

7. A stable base mount as claimed in claim 6, wherein the outer diameterof said cover plate and the outer diameter of said hollow column areequal and wherein the gimbal system is totally enclosed by means of saidcover plate and a bellows the end portions of which are tightly fittedaround the outer circumference of said cover plate and the upperposition of said hollow column.

8. A stable base mount as claimed in claim 1, wherein the lower endportion of said hollow column is secured to a box enclosing said servodrive system.

9. A stable base mount as claimed in claims 1, wherein said servo drivesystem comprises a frame suspended by a second gimbal system havingorthogonal axes, said second gimbal system being mounted in said box ina manner such that the point of intersection of said orthogonal axis islying on the longitudinal axis of said hollow column.

10. A stable base mount as claimed in claim 9, wherein said frame isstabilized about said orthogonal axis by means of direct gearing fromelectric motors to which the roll and pitch error voltages are applied.

11. A stable base mount as claimed in claim 1, wherein said transmissionmeans are constituted by a number of connecting rods linking saidstabilized frame to said base member in a manner such that thecylindrical portion of said base member extends in the vertical whensaid frame is in the horizontal position.

1. A ship-born stable base mount, comprising a hollow column secured ina position perpendicular to a deck plane of the ship, a base member,means for mounting a gimbal system including two orthogonal axes on thetop of the hollow column in a position such that the point ofintersection of the orthogonal axes lies on the logitudinal axis of thehollow column, a gyroscopically controlled servo drive system mounted onthe lower end portion of the hollow column for stabilizing the basemember about the two orthogonal axes, and mechanical transmission meanscontrolled by the servo drive system and extending through the length ofthe interior of the hollow column said transmission means acting on saidbase member whereby said bore member is stabilized about said twoorthogonal axes.
 2. A stable base mount as claimed in claim 1, whereinsaid gimbal system comprises a gimbal ring having two sets of hollowshafts projecting inwardly therefrom to constitute a roll and pitch axisrespectively.
 3. A stable base mount as claimed in claim 2, wherein oneof the hollow shafts constituting the pitch axis accomodates a verticalgyroscope producing error voltages which in magnitude and sensecorrespond to the deviation of said base member from the zero positionas determined by said vertical gyroscope.
 4. A stable base mount asclaimed in claim 1, wherein said hollow column is of circular crosssection and wherein the outer diameter of said gimbal ring is slightlysmaller than the outer diameter of said hollow column.
 5. A stable basemount as claimed in claim 1, wherein said base member comprises acylindrical portion which extends in the vertical when said base memberis stabilized.
 6. A stable base mount as claimed in claim 1, whereinsaid base member is provided with a circular cover plate fixedlyconnected thereto and having a central hole through which thecylindrical portion of said base member protrudes.
 7. A stable basemount as claimed in claim 6, wherein the outer diameter of said coverplate and the outer diameter of said hollow column are equal and whereinthe gimbal system is totally enclosed by means of said cover plate and abellows the end portions of which are tightly fitted around the outercircumference of said cover plate and the upper position of said hollowcolumn.
 8. A stable base mount as claimed in claim 1, wherein the lowerend portion of said hollow column is secured to a box enclosing saidservo drive system.
 9. A stable base mount as claimed in claims 1,wherein said servo drive system comprises a frame suspended by a secondgimbal system having orthogonal axes, said second gimbal system beingmounted in said box in a manner such that the point of intersection ofsaid orthogonal axis is lying on the longitudinal axis of said hollowcolumn.
 10. A stable base mount as claimed in claim 9, wherein saidframe is stabilized about said orthogonal axis by means of directgearing from electric motors to which the roll and pitch error voltagesare applied.
 11. A stable base mount as claimed in claim 1, wherein saidtransmission means are constituted by a number of connecting rodslinking said stabilized frame to said base member in a manner such thatthe cylindrical portion of said base member extends in the vertical whensaid frame is in the horizontal position.